1. Field of the Invention
The invention is related to a device for the strapping with a strapping tape of an essentially cube-shaped or cuboid object and, more particularly, a stack of printed products.
2. Description of Related Art
Known from prior art are various devices, which serve for the strapping of stacks of printed products by means of strapping, particularly a strapping tape. In the case of these devices, a stack of printed products to be strapped is brought to a strapping device by a feeding device, where one or more strapping tapes are laid around the stack. After the strapping, the strapped stack is conducted away from the work zone. Plastic tapes made from polyethyleneterephthalate or polypropylene, for example, are most commonly used.
Strapping means are primarily laid around a stack, (i.e., around a cube-shaped (cuboid) device) in two directions: in the direction of conveyance (longitudinal strapping), in which the stack brought into the work zone, and transverse to the conveyance direction (transverse strapping). While the devices known from prior art can cope with strapping in the transverse direction, strapping in the longitudinal direction with the same devices is, in most cases, associated with certain problems. As a result of the principles involved, parts of the machine are arranged in a manner that interferes with the longitudinal strapping.
From DE 41 00 276 a device is known that comprises a curved, longitudinally slotted channel that is arranged at an angle above and adjacent to a stack of printed products to be strapped. A strapping tape is introduced into the channel, in order to thereupon be laterally pulled out of the channel. Until the tape finally has been laid around a stack to be strapped, it first has to slide over an inclined surface and then has to overcome, at an angle, a free stretch in the air. This arrangement encompasses certain uncertainties because, as a result of the inclined trajectory, it is only poorly possible to determine where the tape will come to lie.
From DE 42 30 730 a further device is known that comprises a static and a movable tape guide channel. This channel is arranged at an oblique angle to a feeding device. In order to be in a position to rationally strap a stack of printed products it is necessary to align it at a corresponding angle relative to the channel.
From EP 0 725 005 a device is known in which a strapping tape is conveyed across a free stretch of air by means of air pressure. This device has the disadvantage that a secure conveyance of the strapping tape across the free stretch of air can only be guaranteed with difficulty. Apart from this, it is only possible to form the tape into a loop after a stack to be strapped has reached a work zone.